What was found
THE CYLINDER HEAD CRACKED AT THE NINETH COOLING FIN. CRACK RUNS ALONG THE FIN. THE CRACK IS ABOUT .5" LONG. THE CYLINDER HAD LOW COMPRESSION. THE CRACK OCCURRED UNDER NORMAL OPERATING CONDITIONS OF A FLIGHT SCHOOL. PROBABLE CAUSE: METAL FATIGUE. THE FOLLOWING NRS ARE ON THE PART: LW-12416, 114085, LW-12307, EQ4E, REV AD, 24713604 OR 24713S04, 131DW.